Adhesives in suspension or in solution in organic solvents are conventionally employed in the manufacture of adhesive tapes. When these adhesives are used it is necessary to carry out a stage of evaporation of the solvent, and this has the result of, on the one hand, limiting the production rate and, on the other hand, producing effluents of toxic character, the removal of which is found to be costly and tricky.
In order to avoid the use of solvents it has been proposed to employ pressure-sensitive hot-melt adhesives.
In WO 93/23488 an adhesive is proposed permitting the adhesive bonding of materials of low surface energy, for example a polyethylene film and a nonwoven fabric. This adhesive includes 75-98% of a diblock copolymer A-B, in which A consists predominantly of polystyrene or its derivatives and B is poly-1,3-butadiene, and a mixture consisting of a solid tackifying resin and of a liquid or oily tackifying resin
In U.S. Pat. No. 5,290,842, a composition is described for the adhesive pasting of labels, which has good cohesion at ambient temperature. This composition includes a first elastomer, for example polybutadiene, and a second elastomer which has a glass transition temperature that is higher than that of the first elastomer, for example polyisoprene, and a tackifying agent which is miscible with the second elastomer.
Patent EP 0104005-A describes an adhesive composition for the adhesive bonding of female protections to garments. This composition includes a viscoelastic polymer of A-B-A type in which B denotes a polyolefin, for example an ethylene-butylene copolymer, and A denotes a polystyrene, and a tackifying resin.
Finally, in WO 93/10734, a positioning adhesive is proposed for female protections on silk, cotton and synthetic fibres. This adhesive includes 6-25% of a copolymer of formula (A-B).sub.n -Y, in which Y is a polyvalent coupling agent, A is a vinyl monomer substituted by an aromatic radical and B is polybutadiene, 30-70% of a compatible tackifying resin and 10-40% of a plasticizing oil.
The pressure-sensitive thermoplastic adhesives which have just been mentioned, while making it possible to avoid the use of solvent, are not, however, completely satisfactory. Thus, the adhesive tapes which are coated therewith exhibit, after being pulled off, a tendency to transfer the adhesive onto the support In addition, the adhesive tapes in contact with the skin exhibit poor resistance to perspiration.